1. Field of the Invention
The present invention relates to ophthalmic lenses, and more particularly, to ophthalmic lenses designed to slow, retard or prevent myopia progression. The ophthalmic lenses of the present invention comprise myopia control optics in combination with muscarinic agents, including atropine, atropine sulphate monohydrate and pirenzepine, to create an effect for increased myopia progression control.
2. Discussion of the Related Art
Myopia or nearsightedness is an optical or refractive defect of the eye wherein rays of light from an image focus to a point before they reach the retina. Myopia generally occurs because the axial length of the eyeball globe is too long or the anterior surface of the cornea is too steep. Myopia affects up to thirty-three (33) percent of the population of the United States and in some parts of the world, up to seventy-five percent of the population. The cause of this refractive error is unknown; however, it is most likely due to a combination of genetic and environmental factors. A minus powered spherical lens may be utilized to correct myopia. The minus powered lens diverges the incoming light rays thereby moving the focal point of the image back onto the macula. As set forth herein, these corrective lenses treat myopia, but do not prevent the progression of myopia.
A number of methods to slow or retard myopia progression, especially in children, have been proposed and developed. These methods including utilizing multi-focal lenses, utilizing lenses with one or more aberrations introduced therein, utilizing lenses which control aberrations, utilizing off axis power lenses, reshaping the cornea, exercising the eye and utilizing pharmacological or drug therapies.
The use of multi-focal lenses and those having aberrations have proved to be somewhat disadvantageous in that the lenses may compromise the wearer's distance vision and have limited treatment efficacy of around thirty (30) percent to fifty (50) percent of axial elongation or refractive difference to age matched control group as shown in a number of published studies. The other methods set forth above also suffer from disadvantages, including discomfort, as with the corneal reshaping, and potentially undesirable side effects, as with the pharmacological or drug therapies. Specifically, atropine, a non-selective muscarinic agent, has been shown in a number of studies to be useful in the treatment of myopia.
Accordingly, there exists a need for a therapy for at least one of inhibiting, preventing and/or controlling the progression of myopia that combines the benefits of one or more individual therapies in order to achieve a desired effect while minimizing the disadvantages of currently available therapies.